The closest prior art I am familiar with is patent application Ser. No. 849,171, filed Nov. 7, 1977, to Frederick J. Kozacka for FUSE HAVING NOVEL FUSIBLE ELEMENT AND PROCESS OF MANUFACTURING SAID ELEMENT, now U.S. Pat. No. 4,153,892.
In manufacturing electric fuses for elevated circuit voltages the problem arises of winding a plurality of fusible elements in equidistantly substantially helical turns around planes which define a prismatic solid. To this end the edges of that solid are either marked equidistantly, or provided with recesses which support the fusible elements equidistantly. The helical winding of the individual elements is effected one after the other, or sequentially. A build-up of such a fuse is expensive because of the plurality of winding operations involved.
The above Kozacka patent proposes to produce composite fusible elements which can be wound simultaneously around a helical surface rather than in sequential steps. This is achieved by members of insulating material tying together the fusible elements at equidistantly spaced, fixed points thereof. The spacing of the fixed points is such that the members are situated between the edges of the prism rather than at the edges thereof when the plurality of fusible elements is wound around the prism.
The way of manufacturing fusible elements disclosed in the above Kozacka application achieves the intended goal, but at relatively high cost because the tying together of fusible elements by insulating members is a rather complex, rather labor intensive operation. Kozacka has the advantage that his fusible element tying means also perform the secondary function of arc-voltage control, because they subdivide the fusible elements into zones which are directly exposed to the quenching action of the pulverulent arc-quenching filler, and into other zones where the arc-quenching filler is not directly acting upon the arc. However, this secondary beneficial effect of the insulating members of Kozacka can be achieved according to the present invention by simpler means, as will be shown below in greater detail.
It is, therefore, the primary object of the present invention to achieve the same, or substantially the same, results as the aforementioned patent application of Kozacka in a more cost-effective way.
Other object of this invention and advantages thereof will become apparent as this specification proceeds.